1. Field of the Invention
The present invention relates to a solid electrolytic capacitor characterized in its structure and a method for manufacturing same.
2. Description of Related Art
FIG. 26 is a cross-sectional view of a conventional solid electrolytic capacitor. As shown in FIG. 26, the conventional solid electrolytic capacitor comprises a capacitor element 100, an exterior resin 106 covering the capacitor element 100, an anode terminal 107, and a cathode terminal 108. The capacitor element 100 is formed by, on an outer peripheral surface of an anode body 101 from which a part of an anode lead 102 is extracted, sequentially forming a dielectric layer 103, an electrolyte layer 104, and a cathode layer 105 in this order. The anode terminal 107 is directly connected to an extraction part 102a of the anode lead 102, while the cathode terminal 108 is connected to the cathode layer 105 of the capacitor element 100 via a conductive adhesive 109.
FIG. 27 is a cross-sectional view of a conventional solid electrolytic capacitor showing a base part of the extraction part 102a of the anode lead 102 in a magnified scale. In a molding process for covering the capacitor element 100 with the exterior resin 106, due to curing shrinkage of the exterior resin 106, a stress is applied to the anode lead 102. Therefore, conventional solid electrolytic capacitors are likely to have a problem such that the stress concentrates on the base part of the extraction part 102a of the anode lead 102 to generate a crack or the like on the dielectric layer 103 as shown in FIG. 27, resulting in an increase in leakage current.
In view of this, considered is a countermeasure to fix the base part of the extraction part 102a of the anode lead 102 with a thermoset resin to enhance the strength of the base part of the extraction part 102a of the anode lead 102 against the curing shrinkage of the exterior resin 106, resulting in prevention of the occurrence of cracks.
However, in conventional solid electrolytic capacitors, it is not possible to sufficiently relax a stress generated in welding the anode lead 102 and the anode terminal 107 to each other. Therefore, the stress generated in the welding possibly concentrates on the base part of the extraction part 102a of the anode lead 102 to generate a crack on the dielectric layer 103, resulting in an increase in leakage current.
Also, in conventional solid electrolytic capacitors, it is not possible to sufficiently relax a stress applied to the anode lead 102 in an axial direction thereof. Therefore, due to curing shrinkage of the exterior resin 106, the extraction part 102a of the anode lead 102 is possibly pressed toward the capacitor element 100, resulting in intrusion of the extraction part 102a in the capacitor element 100. When the extraction part 102a is intruded in the capacitor element 100, a crack or the like occurs on the dielectric layer 103 of the capacitor element 100 and the leakage current increases.